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Abstract:

A filling method exhausts gas from inside a slit nozzle that applies
coating liquid onto a substrate surface while filling the slit nozzle
with the coating liquid. The slit nozzle includes a coating liquid supply
opening, a coating liquid discharge outlet, a manifold that is connected
to the supply opening and holds the coating liquid inside the slit
nozzle, a liquid channel that is connected to the manifold and supplies
the coating liquid to the discharge outlet of the slit nozzle, and a
ventilation hole for exhausting gas from inside the manifold. The filling
method includes: a discharge outlet closing process that closes the
discharge outlet while the coating liquid is being fed from the supply
opening into the slit nozzle; and a ventilation hole opening process that
opens the ventilation hole.

Claims:

1. A coating liquid filling method that fills an inside of a slit nozzle,
which applies coating liquid with a predetermined width onto a surface of
a processed object, with the coating liquid, wherein the slit nozzle
includes a supply opening that is a supply portion for the coating
liquid, a discharge outlet that is a discharge portion for the coating
liquid, a manifold that is connected to the supply opening and holds the
coating liquid inside the slit nozzle, a liquid channel that is connected
to the manifold and supplies the coating liquid toward the discharge
outlet of the slit nozzle, and a ventilation hole for exhausting gas from
inside the manifold, the coating liquid filling method comprising: a
discharge outlet closing process that closes the discharge outlet; and a
ventilation hole opening process that opens the ventilation hole, the
discharge outlet closing process and the ventilation hole opening process
being carried out while the coating liquid is being fed from the supply
opening into the slit nozzle

2. The coating liquid filling method according to claim 1, wherein a
feeding process that feeds the coating liquid into the slit nozzle is a
process where filling of the manifold with the coating liquid is
completed after filling the liquid channel with the coating liquid.

3. The coating liquid filling method according to claim 1, wherein the
discharge outlet closing process is carried out before filling the liquid
channel with the coating liquid is commenced.

4. The coating liquid filling method according to claim 1, wherein the
slit nozzle has a plurality of ventilation holes, the respective
ventilation holes are opened and closed by the ventilation hole opening
process and a ventilation hole closing process that are carried out for
each ventilation hole, and opening and closing of the ventilation holes
are controlled so that at least one of the ventilation holes is open.

5. The coating liquid filling method according to claim 1, further
comprising: a process that opens the discharge outlet that is in a closed
state after an end of the feeding process that feeds the coating liquid
into the slit nozzle; and a process that subsequently scrapes away
coating liquid that has come out of the discharge outlet.

6. The coating liquid filling method according to claim 2, further
comprising: a process that opens the discharge outlet that is in a closed
state after an end of the feeding process that feeds the coating liquid
into the slit nozzle; and a process that subsequently scrapes away
coating liquid that has come out of the discharge outlet.

7. The coating liquid filling method according to claim 1, wherein the
discharge outlet closing process is a process that closes the discharge
outlet by placing a discharge outlet closing member in contact with the
discharge outlet, and the process that opens the discharge outlet that is
in the closed state is a process that separates the discharge outlet
closing member from the discharge outlet.

8. The coating liquid filling method according to claim 3, wherein the
discharge outlet closing process is a process that closes the discharge
outlet by placing a discharge outlet closing member in contact with the
discharge outlet, and the process that opens the discharge outlet that is
in the closed state is a process that separates the discharge outlet
closing member from the discharge outlet.

9. The discharge outlet closing member used in the coating liquid filling
method according to claim 7.

10. A slit nozzle unit comprising a slit nozzle that applies a coating
liquid onto a surface of a processed object with a predetermined width,
wherein the slit nozzle includes a supply opening that is a supply
portion for the coating liquid, a discharge outlet that is a discharge
portion for the coating liquid, a manifold that is connected to the
supply opening and holds the coating liquid inside the slit nozzle, a
liquid channel that is connected to the manifold and supplies the coating
liquid toward the discharge outlet of the slit nozzle, and a ventilation
hole for exhausting gas from inside the manifold, and the slit nozzle
unit further comprises a discharge outlet closing member used to close
the discharge outlet while the coating liquid is being fed from the
supply opening into the slit nozzle.

11. A slit nozzle unit according to claim 10, wherein the discharge
outlet closing member is constructed by covering a periphery of a core
member, which is a main portion, with an elastic body.

Description:

1. FIELD OF THE INVENTION

[0001] The present invention relates to a slit nozzle that discharges a
coating liquid to form a coated film, a coating liquid filling method for
such slit nozzle, a discharge outlet closing member used when filling
with such coating liquid, and a slit nozzle unit including such discharge
outlet closing member.

2. DESCRIPTION OF THE RELATED ART

[0002] Slit coating carried out using a slit nozzle is one method of
forming a coating film on the surface of a glass substrate for a liquid
crystal display, a semiconductor wafer, or the like. Such method forms a
coated layer by discharging a coating liquid, which fills a manifold
inside the slit nozzle, from a slit-shaped discharge outlet of the slit
nozzle.

[0003] As the apparatus that forms a coated layer with a method such as
slit coating, an apparatus capable of forming a high-quality coated
layer, such as a coating layer of a uniform thickness, is desirable.

[0004] One example of an apparatus that carries out slit coating is a
coating processing apparatus equipped with a slit nozzle with an
air-bleeding hole that removes air from inside the manifold (see Patent
Document 1).

[0005] The slit nozzle of such apparatus is equipped with supply openings
formed in both side ends of the manifold and an air-bleeding hole formed
in an upper center of the manifold, and when resist solution is supplied
into the manifold from both supply openings, air is bled out from the
central air-bleeding hole so that the manifold becomes filled with the
resist solution. Also, the upper surface of the manifold of such
apparatus is formed so as to be inclined with rising slopes from the
supply holes at both ends toward the lower end of the air-bleeding hole
at the upper center. By forming the manifold in the shape described
above, it is possible to easily and reliably remove air inside the
manifold and moreover possible to obtain a uniform coated layer that does
not include air bubbles. This means that by opening the air-bleeding hole
for a certain period before the start of the coating process to remove
gas from inside the manifold while filling the manifold with the coating
liquid, the pressure of the coating liquid discharged from the discharge
outlet can be regulated so as to be uniform and the coating process will
start after the coating liquid to be discharged from the discharge outlet
has been arranged into a straight line.

[0008] However, a slit nozzle 100 is equipped with a liquid channel 102
that joins the coating liquid to the discharge outlet below a manifold
101 (see FIG. 7). In this slit nozzle 100, the coating liquid L flows
from the manifold 101 via the liquid channel 102 to the discharge outlet
103 at the front end of the nozzle. When forming a thin coated layer with
a coating liquid with low viscosity, the width of the liquid channel 102
will be around several tens of micrometers and the coating liquid L will
spread out as far as the corners of the manifold 101 before the liquid
reaches the discharge outlet 103, making it possible to bleed air out
from inside the manifold 101 without any problems.

[0009] However, as the viscosity of the coating liquid L increases, higher
pressure and more time become necessary as the pressure and time for
extruding the liquid, and the width of the liquid channel 102 of the slit
nozzle 100 also needs to be increased.

[0010] When the width of the liquid channel is increased, there is a
tendency for the coating liquid L to reach the discharge outlet 103 at an
earlier time, so that the coating liquid may spill out from the discharge
outlet 103 before the coating liquid has spread out to the corners of the
manifold 101 (i.e., before the manifold has become filled with the
coating liquid) (see FIG. 7).

[0011] The present invention was conceived in view of the problems
described above and has an object of providing a coating liquid filling
method capable of favorably carrying out the bleeding of air at a slit
nozzle with a wide slit for use with highly-viscose liquids, and to also
provide a discharge outlet closing member used in such a slit nozzle and
a slit nozzle unit.

[0012] A coating liquid filling method that fills an inside of a slit
nozzle, which applies coating liquid with a predetermined width onto a
surface of a processed object, with the coating liquid, wherein the slit
nozzle includes a supply opening that is a supply portion for the coating
liquid, a discharge outlet that is a discharge portion for the coating
liquid, a manifold that is connected to the supply opening and holds the
coating liquid inside the slit nozzle, a liquid channel that is connected
to the manifold and supplies the coating liquid toward the discharge
outlet of the slit nozzle, and a ventilation hole for exhausting gas from
inside the manifold, the coating liquid filling method comprising: a
discharge outlet closing process that closes the discharge outlet; and a
ventilation hole opening process that opens the ventilation hole, the
discharge outlet closing process and the ventilation hole opening process
being carried out while the coating liquid is being fed from the supply
opening into the slit nozzle.

[0013] The feeding process that feeds the coating liquid into the slit
nozzle may be a process where filling of the manifold with the coating
liquid is completed after filling the liquid channel with the coating
liquid.

[0014] The discharge outlet closing process may be carried out before
filling the liquid channel with the coating liquid is commenced.

[0015] The slit nozzle may have a plurality of ventilation holes, the
respective ventilation holes may be opened and closed by the ventilation
hole opening process and a ventilation hole closing process that are
carried out for each ventilation hole, and opening and closing of the
ventilation holes may be controlled so that at least one of the
ventilation holes is open.

[0016] The coating liquid filling method may further include: a process
that opens the discharge outlet that is in a closed state after an end of
the feeding process that feeds the coating liquid into the slit nozzle;
and a process that subsequently scrapes away coating liquid that has come
out of the discharge outlet.

[0017] The discharge outlet closing process may be a process that closes
the discharge outlet by placing a discharge outlet closing member in
contact with the discharge outlet, and the process that opens the
discharge outlet that is in the closed state may be a process that
separates the discharge outlet closing member from the discharge outlet.

[0018] Another aspect of the present invention is the discharge outlet
closing member used in the coating liquid filling method described above.

[0019] Yet another aspect of the present invention is a slit nozzle unit
including a slit nozzle that applies a coating liquid onto a surface of a
processed object with a predetermined width, wherein the slit nozzle
includes a supply opening that is a supply portion for the coating
liquid, a discharge outlet that is a discharge portion for the coating
liquid, a manifold that is connected to the supply opening and holds the
coating liquid inside the slit nozzle, a liquid channel that is connected
to the manifold and supplies the coating liquid toward the discharge
outlet of the slit nozzle, and a ventilation hole for exhausting gas from
inside the manifold, and the slit nozzle unit further includes a
discharge outlet closing member used to close the discharge outlet while
the coating liquid is being fed from the supply opening into the slit
nozzle.

[0020] Yet another aspect of the present invention is a slit nozzle unit
including a slit nozzle that applies coating liquid with a predetermined
width onto a surface of a processed object and the discharge outlet
closing member described above.

[0021] The discharge outlet closing member may be constructed by covering
a periphery of a core member, which is a main portion, with an elastic
body.

[0022] The coating liquid applying method according to the present
invention is capable of filling a manifold with coating liquid both
quickly and reliably. The coating liquid applying method according to the
present invention is also favorable as a coating liquid applying method
for a slit nozzle with a wide slit. By filling with coating liquid using
this method, it is possible in a subsequent coating process to more
reliably form a coated layer with a uniform thickness. Also, by using the
discharge outlet closing member and slit nozzle unit according to the
present invention, it is possible to carry out the coating liquid filling
method according to the present invention more reliably.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a perspective view showing a liquid coating apparatus to
which a slit nozzle, which is filled with coating liquid by a coating
liquid filling method according to the present invention, is attached;

[0030] FIG. 8 is a block diagram showing a controller and objects being
controlled; and

[0031] FIG. 9 is a flowchart showing the flow of operations in the coating
liquid filling method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Next, embodiments of a coating liquid filling method, a slit
nozzle, a discharge outlet closing member, and a slit nozzle unit
according to the present invention will be described.

[0033] This coating liquid filling method is used when filling the slit
nozzle provided in a liquid coating apparatus with coating liquid. For
this reason, a liquid coating apparatus will be described first. The
liquid coating apparatus is an apparatus for coating a plate material,
such as a substrate, with a thin coated film (while leaving the edges
uncoated).

[0034] As shown in FIG. 1, the liquid coating apparatus 1 is equipped with
a base 2 and a table 3 for a plate material which is installed at a
center portion on the base 2. Such table 3 is a table on which a plate
material 4, which is the object to be coated (i.e., the "processed
object"), is placed. Side walls 2a, 2b that are erected at right angles
are respectively formed on both side edges of the base 2, and rails 5a,
5b are laid out on the upper surfaces of such side walls 2a, 2b. A
coating mechanism unit 10 is installed so as to be capable of moving on
such rails 5a, 5b.

[0035] A slit nozzle 20, with a discharge outlet 29 (see FIGS. 3 and 4)
described later at the lower end thereof, is installed on the coating
mechanism unit 10 so as to be capable of being raised and lowered.
Accordingly, when coating liquid is applied onto the surface of the plate
material 4 placed on the table 3, the coating mechanism unit 10 is moved
and the coating liquid is discharged from the discharge outlet 29 at the
lower end of the slit nozzle 20. By doing so, the coating liquid is
applied with a predetermined width onto the surface of the plate material
4 to form a coated layer with a predetermined width.

[0036] Note that operations in the liquid coating apparatus, such as a
driving operation of a driving mechanism 11 that drives the coating
mechanism unit 10, a raising/lowering operation of a raising/lowering
mechanism 12 that raises and lowers the slit nozzle 20, and an
opening/closing operation of an opening/closing device 32 that opens and
closes ventilation holes 31, described later, are controlled by a
controller (control unit) S of the liquid coating apparatus (see FIG. 8).
Since such controller S is a well-known device, detailed description
thereof is omitted here.

[0037] The slit nozzle 20 can be detachably attached to the liquid coating
apparatus 1 and, as shown in FIG. 2, is constructed from two nozzle
pieces 21, 22 into which the nozzle is split and a shim 23 that is
combined so as to be sandwiched between both nozzle pieces 21, 22. The
two nozzle pieces 21, 22 are both slim blocks made of metal (stainless
steel) and are installed on the coating mechanism unit 10 in a state
where the discharge outlet 29 faces downward. In the following
description, the up-down direction is described with the installed state
on the coating mechanism unit 10 as a reference.

[0038] The respective nozzle pieces 21, 22 have contact surfaces 21b, 22b
(see FIG. 4) that face one another when the nozzle pieces 21, 22 are
combined and include protruding portions 21a, 22a that protrude at an
acute angle provided at lower end portions of the contact surfaces 21b,
22b. When the two nozzle pieces 21, 22 are combined, the discharge outlet
29 (see FIG. 3), described later, is formed by such protruding portions
21a, 22a.

[0039] Out of the nozzle pieces 21, 22, the first nozzle piece 21 is
equipped with a manifold 26 that is an internally-formed space, a coating
liquid supply opening 24 used to supply the coating liquid to the
manifold 26, and a plurality of ventilation holes 31a, 31b that pass
through to the manifold 26.

[0040] The coating liquid supply opening (coating liquid supply hole) 24
is a supply portion (supply channel) for the coating liquid. The coating
liquid supply opening 24 has an upper end opening 24a formed in a center
portion in the length direction X of the upper surface of the first
nozzle piece 21 and a lower end opening 24b that is open to the manifold
26 side, and passes through to the manifold 26.

[0041] The manifold 26 is provided so as to cause the coating liquid
supplied from the coating liquid supply opening 24 to spread out in the
length direction (the length direction of the slit nozzle 20) X and
extends in the length direction X of the slit nozzle 20. The manifold 26
has an opening 26a formed in the contact surface 21b of the first nozzle
piece 21.

[0042] The ventilation holes 31a, 31b are used to exhaust gas inside the
manifold 26 and each include a lower end opening that is open to the
manifold 26 side and an upper end opening that is open to the outside of
the slit nozzle 20. As one example, there are two ventilation holes 31a,
31b and such holes are formed on the respective sides in the length
direction of the upper surface of the first nozzle piece 21 so as to be
positioned on both sides of the coating liquid supply opening 24.
Although it is possible to provide one ventilation hole or three or more
ventilation holes, in view of the ability to exhaust gas, it is
preferable to have an even number of holes to achieve line symmetry.
Also, since an opening/closing means that is an opener/closer, such as a
valve, for opening and closing the ventilation holes is a known device,
detailed explanation thereof is omitted here.

[0043] The shim 23 is a thin plate-like material formed in a U shape and
is equipped with a concave portion 23a. The shim 23 is assembled between
the two nozzle pieces 21, 22 in a state where an open end of the concave
portion 23a faces downward. By assembling the shim 23 so as to be
interposed between the nozzle pieces 21, 22, a liquid channel space 28 is
formed inside the slit nozzle 20 and a slit-shaped discharge outlet 29 is
also formed at the bottom end of the slit nozzle 20. Accordingly, by
adjusting the thickness of the shim 23, it is possible to adjust the slit
width W (see FIG. 4) of the liquid channel space 28 and the discharge
outlet 29. Also, by adjusting the length in the length direction X of the
concave portion 23a, it is possible to adjust the length in the length
direction X of the discharge outlet 29.

[0044] Also when the slit nozzle 20 has been produced by assembling the
two nozzle pieces 21, 22 and the shim 23, the opening 26a of the manifold
26 will face the liquid channel space 28 (see FIG. 3) formed by the
concave portion 23a of the shim 23. That is, an upper end portion of the
liquid channel space 28 passes through to the manifold 26.

[0045] Accordingly, the coating liquid supplied from the coating liquid
supply opening 24 flows into the manifold 26, is held inside the manifold
and is caused to spread out in the length direction X. After this, the
coating liquid flows into the liquid channel space 28 and is discharged
via the liquid channel space 28 from the discharge outlet 29. Note that
if the ventilation holes 31a, 31b are provided, it is easy for air inside
the manifold 26 to escape to the outside, which promotes dispersion in
the length direction X of the coating liquid inside the manifold 26.

[0046] Also, as shown in FIG. 1, the liquid coating apparatus 1 is
equipped with a maintenance mechanism 40 for the slit nozzle 20 that is
installed in front of (i.e., to the lower left in FIG. 1) the table 3 and
a filling table 50 used when filling the slit nozzle 20 with the coating
liquid.

[0047] The maintenance mechanism 40 is equipped with a sliding portion 48
that is capable of being pulled out in the width direction of the
maintenance mechanism. When the sliding portion 48 is pulled out in the
width direction (refer to the position shown with the dot-dot-dash line
in FIG. 1), it becomes possible to remove or load the slit nozzle 20 from
or onto the sliding portion 48. Once the slit nozzle 20 has been loaded
onto the sliding portion 48 and the sliding portion 48 has then been
returned to its original position, the slit nozzle 20 becomes placed on
the maintenance mechanism 40. After this, when the coating mechanism unit
10 has moved to a position above the slit nozzle 20, it becomes possible
to attach the slit nozzle 20 to the coating mechanism unit 10. In this
way, the slit nozzle 20 can be attached to and detached from the liquid
coating apparatus 1.

[0048] The filling table 50 is equipped with a filling bar (discharge
outlet closing member) 51 that is detachably installed.

[0049] The filling bar 51 is used to close the discharge outlet of the
slit nozzle 20 and as shown in FIGS. 3 and 4, is constructed of a
bar-shaped core member (rigid body) 52 as a main body and a peripheral
elastic member 53 that covers the core member 52. That is, the surface of
the upper portion on the discharge outlet 29 side is constructed of an
elastic material. Accordingly, when the discharge outlet 29 is closed
using the filling bar 51, it is possible to reliably close the discharge
outlet 29 using the filling bar 51. Since the filling bar 51 has the
bar-shaped core member 52 inside, it is possible to reliably close the
discharge outlet 29 without the filling bar 51 greatly deforming or
bending when the discharge outlet 29 is closed by the filling bar 51.
Since the elastic member 53 is specifically a rubber material, there is
no damage to the discharge outlet 29 of the slit nozzle 20 when the
discharge outlet 29 of the discharge outlet 29 is closed using the
filling bar 51.

[0050] In this way, the filling bar 51 is used when filling the slit
nozzle 20 with the coating liquid, and it is possible to regard the slit
nozzle 20 and the filling bar 51 as a unit (slit nozzle unit) 15.

[0051] Next, a coating liquid filling method that fills the slit nozzle of
a liquid coating apparatus such as that described above with coating
liquid will be described with reference to the flowchart shown in FIG. 9.

[0052] Here, the procedure of the coating liquid filling method will be
described with a state where all of the ventilation holes are closed and
the inside of the slit nozzle 20 has not been completely filled with the
coating liquid as a starting point (see FIG. 6A).

[0053] Also, since a controller (see FIG. 8) for starting and ending the
supplying of coating liquid, carrying out opening and closing the
ventilation holes and/or a raising/lowering operation for moving the
filling bar toward and away from the discharge outlet is a known control
means, detailed description thereof is omitted here.

[0054] Filling with the coating liquid first starts with feeding the
coating liquid into the slit nozzle 20 from the coating liquid supply
opening 24 (feeding start process).

[0056] After this, during feeding, the discharge outlet 29 is closed by
the filling bar 51 (discharge outlet closing process, see FIG. 6B). Note
that the timing for closing the discharge outlet 29 is specifically
before the coating liquid starts flowing inside the liquid channel space
28.

[0057] By using the filling bar 51 in this way to close the discharge
outlet 29, the coating liquid L is prevented from flowing out of the
discharge outlet 29 during filling. If it is possible to prevent the
coating liquid from flowing out of the discharge outlet 29, there will be
no wasting of the coating liquid and dirtying of the periphery by coating
liquid that has flowed out is prevented.

[0058] Also, during feeding, the ventilation holes are opened (ventilation
hole opening process, see FIG. 6C).

[0059] Note that the timing for the initial ventilation hole opening
process (the timing at which the ventilation hole opening/closing process
starts) is before the coating liquid starts to flow into (fill) the
liquid channel.

[0060] More specifically, the ventilation hole opening/closing process
starts with opening one of the ventilation holes (the ventilation hole
31a) (ventilation hole opening process). Here, the ventilation hole 31a
shown on the left in FIG. 2 is opened from the closed state. At this
time, the other ventilation hole 31b is kept in the closed state (see
FIG. 6C).

[0061] After this, once a predetermined period has elapsed, the one
ventilation hole 31a that was opened in the preceding opening state is
closed (i.e., a ventilation hole closing process is carried out) and
together with this the other ventilation hole 31b is opened (ventilation
hole opening process, see FIG. 6D). That is, the ventilation hole closing
process for one ventilation hole 31a and the ventilation hole opening
process for the other ventilation hole 31b are carried out together. In
addition, when the predetermined period has elapsed, the first
ventilation hole 31a is opened and together with this the ventilation
hole 31b is closed.

[0062] In this way, in the ventilation hole opening/closing process, an
opening/closing operation that alternately opens and closes is repeatedly
carried out at intervals of a predetermined period. Putting this another
way, in the ventilation hole opening/closing process, as one example a
control means (not shown) is used to first control the opening of at
least one of the ventilation holes and also control the closing of the
remaining ventilation holes, and after that to successively control the
opening and closing of the ventilation holes. After this, the ventilation
hole opening/closing process is carried out at least until the gas inside
the manifold 26 has been completely exhausted and the manifold 26 is
filled with the coating liquid. The time for which the ventilation holes
are open is appropriately set in accordance with the viscosity of the
coating liquid and/or the number of ventilation holes.

[0063] In this way, some of the ventilation holes (for example, one of the
ventilation holes 31a) is opened, the coating liquid is introduced into
the manifold 26, and since air and bubbles inside the manifold 26 escape
from the open ventilation holes to the outside, it is possible for the
introduced coating liquid to efficiently flow and spread out inside the
manifold 26 toward the ventilation hole(s) in the open state. A method of
filling with coating liquid in the manner described above is especially
effective when high pressure is required as the filling pressure and/or
when a long time is required as the filling time, such as when filling
with a highly viscose coating liquid.

[0064] Also, by successively changing which ventilation holes are open, it
is possible to cause the coating liquid to flow efficiently within the
entire manifold 26. In addition, by repeating the operation of changing
the ventilation holes that are open whenever a predetermined period has
elapsed, it is possible to cause the coating liquid to flow more reliably
to all of the corners inside the manifold. Accordingly, during the
ventilation hole opening/closing process, the number of times the
ventilation holes are opened should preferably be at least twice for each
ventilation hole.

[0065] Also, if the feeding of liquid into the slit nozzle 20 continues,
some of the coating liquid that is held inside the manifold 26 will
subsequently start to flow inside the liquid channel space 28. After
that, the feeding of liquid further continues, the liquid channel space
28 becomes filled with the coating liquid, and after this, when the
inside of the manifold 26 has become filled with the coating liquid, the
feeding of liquid into the slit nozzle 20 ends (see FIG. 6E).

[0066] Once the feeding of liquid into the slit nozzle 20 has ended, the
filling bar (discharge outlet closing member) 51 is separated from the
discharge outlet 29 (separating process, see FIG. 6F).

[0067] After the end of filling, since the filling bar 51 that closes the
discharge outlet 29 has contacted the coating liquid in the liquid
channel space 28, when the filling bar 51 is separated from the discharge
outlet 29, an extremely small amount of coating liquid La is pulled by
the filling bar 51 and is brought out of the discharge outlet 29 (see
FIG. 6F).

[0068] If no filling bar 51 were present, during filling, coating liquid
that has reached the discharge outlet 29 would flow out from the
discharge outlet. However, by using the filling bar 51 as in the present
embodiment, such situation is prevented.

[0069] After the filling bar has been separated from the discharge outlet,
a wiping process is carried out as necessary to wipe away extra coating
liquid that adheres to the discharge outlet 29 of the slit nozzle 20 and
thereby regulate the state of the front end of the coating liquid
discharged from the discharge outlet 29.

[0070] Although the discharge outlet 29 is closed with the filling bar 51
during filling, there are cases where a small amount of the coating
liquid flows out to the periphery of the discharge outlet 29 during
filling. For this reason, the wiping process is carried out after filling
with liquid and before the start of coating. By doing so, it is possible
to scrape away liquid that has adhered to the discharge outlet 29. After
this, coating is commenced.

[0071] As the member used for wiping, it is possible to use a member such
as a so-called V-shaped rubber pad and a plate-like member that wipes the
open end of the discharge outlet 29.

[0072] By doing so, when filling of the slit nozzle 20 with the coating
liquid ends, it is possible to start the coating process that coats a
predetermined width of the surface of the plate material 4, which is the
surface of the processed object, with the coating liquid to form a coated
layer.

[0073] Note that the coating liquid filling method, slit nozzle, discharge
outlet closing member, and slit nozzle unit according to the present
invention are not limited to the examples in the embodiments described
above. It is possible to apply modifications without departing from the
scope of the present invention, and such modifications are also included
in the present invention.

[0074] As examples, as the timing for closing the discharge outlet 29
(discharge outlet closing process), it is possible to use timing before
the coating liquid reaches the discharge outlet 29, timing before filling
the manifold 26 with the coating liquid starts, the same timing as the
start of the feeding process, and timing before the start of the feeding
process.

[0075] Also, as the timing of the start of the ventilation hole opening
process, it is possible to use timing before the start of filling the
manifold 26 with the coating liquid, the same timing as the start of the
feeding process, and timing before the start of the feeding process.

[0076] The number of ventilation holes to be opened in the ventilation
hole opening process is also not limited to one. If a plurality of
ventilation holes are provided, it is possible to bleed out the air
inside the manifold 26 in a short time. So long as at least one
ventilation hole is open during this process, the other ventilation holes
may be open or may be closed.

[0077] In the ventilation hole opening/closing process, if the ventilation
hole opening process for one ventilation hole and the ventilation hole
closing process for another ventilation hole are carried out together, as
the timing for carrying out both processes, aside from having such
processes carried out at the same timing as in the embodiment described
earlier, it is possible to carry out the ventilation hole closing process
on some holes first and then carry out the ventilation hole opening
process on other holes or to carry out the ventilation hole opening
process on some holes first and then carry out the ventilation hole
closing process on other holes.

[0078] The timing for ending the ventilation hole opening/closing process
is also not limited to a filling completion time for filling the manifold
26 with the coating liquid that has been measured in advance, and it is
possible to use a sensor that detects whether the coating liquid has
reached the ventilation holes and to carry out the ventilation hole
opening/closing process until such sensor reacts.

[0079] As the filling bar 51, as one example it is possible to use a bar
whose upper portion on the discharge outlet 29 side is a flat upper
surface 53a. It is also possible for the upper surface of the core member
52 positioned at the upper side of the filling bar 51 to be flat. Also,
although the width of the upper surface of the filling bar 51 is wider
than the slit width W of the discharge outlet 29 of the slit nozzle 20,
it is also possible for the width of the upper surface of the core member
52 to be wider than the slit width W of the discharge outlet 29.

[0080] Also, as described earlier, if the discharge outlet 29 is closed
using the filling bar 51, it is possible to prevent the coating liquid
from leaking out from the discharge outlet 29 during a coating liquid
filling operation. Accordingly, the discharge outlet closing process can
be referred to as a process that moves the filling bar 51 from a
separated position that is separated from the discharge outlet to a
closed position that prevents the coating liquid from leaking out during
filling. Also, as the discharge outlet closing process that closes the
discharge outlet 29 using the filling bar 51 (see FIG. 6B), a method
utilizing an operation of having the filling bar 51 press against (i.e.,
contact) the discharge outlet 29 and an operation of bringing the filling
bar 51 close to the discharge outlet 29 can be given as examples.

[0081] Also, as described earlier, the inventions described in this
application are favorable as a slit nozzle for coating with a highly
viscous coating liquid and a coating liquid filling method that uses such
slit nozzle.

[0082] More specifically, this is a bubble removing method that is
effective in a case where the slit width is around 100 to 600 μm, the
viscosity of the liquid is in a range of 1,000 to 5,000 cps and the
coating liquid would reach the discharge outlet before spreading out
inside the manifold.